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Having trouble about importing 3D geometry

March 13, 2015, 12:42 am
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When I am trying to import a 3D geometry file named XX.SLDPRT(a Solidworks file) or XX.ipt(Inventor file), it turns out to show: D:\Program Files\COMSOL\COMSOL50\Multiphysics\lib\win64\csjcad.dll: Can't find dependent libraries. (attached file)
How should I do? There is no problem when I'm importing mphbin file.
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Integral over a ploted line

March 13, 2015, 5:54 am
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Hi

I plotted the electric field lines with some conditions in my model but now I just want to get the integral of ONE ELECTRIC FIELD LINE plotted. How can I do this.?
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"Contact Pressure" vs. "Pressure"?

March 13, 2015, 6:47 am
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When I compute "contact pressure" and "pressure" on the contact boundary and export the data, I get different answers (attached).

Does anyone know how does COMSOL caluclates "contact pressure" differently than "pressure"?

Thanks!

Daniel
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COMSOL giving error on OS X

March 13, 2015, 10:36 am
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COMSOL 5 is continuously showing "unexpected error" and stops working.
Screenshot and log file has been attached.
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User defined PDE

March 13, 2015, 11:04 am
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Can someone write the attached PDE in its coefficient form.
Regards
Subramanian Aiyer
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Nitrogen plasma simulation: cross section file?

December 15, 2010, 7:33 am
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Hello,

I followed the webinar about plasma simulation, and they told something about
a french institut in Toulouse who was supposed to provide the cross sections
data for different gases.like the argon.txt.. but for nitrogen..

Anyone that took more attention than me?

Can somebody help on that? any file that would help getting away from Argon?

Thank you

Lukas
Germany
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Having Difficulty Defining Current In 3D Magnet Coil + Meshing Issue

February 23, 2011, 6:35 am
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Hello all,

Firstly, I just would like to thank you for any help in advanced, since I am currently a bit stuck on a certain problem. I am just starting to use COMSOL in my work and so I may just be missing something simple but I am finding no easy answer to defining a constant current / current density to run through a simplified Stellarator magnet design.

The fact that this is a 3D magnet that is not symmetrical I cannot think of simple equations to use to generate a constant current density using the External Current Density feature as you could with say a circular coil. So I am wondering if there is another option than trying to deduce equations for the x,y, and z parameters of the current density of this coil to generate the appropriate current? The only real parameter to note is that the defined current for this magnet design to be running through the copper coils is -1.773333e+05 A. This simple model was generated first in Solidworks and then imported over to COMSOL for analysis of the Magnetic Flux and the magnetic stress on the coil for a start.

Another problem worth mentioning is that the coil will be made up of 45 coil packs connected together like this one with each rectangular coil of copper having a circular cut out where active water cooling will run. In attempts to mesh just one of these coil packs with an inner cylinder of water, the meshing would always give an error that says that it fails to generate the mesh for a certain domain, or says an error is due to an edge or boundary problem. I hope someone can shed some light on these issues, thanks.

The first attached model is the simplified single coil with no water cooling. ( focused on the current definition issue)
The 2nd attached model is one coil with the inside cylinder for water cooling ( focused on mesh issue )

-Joshua
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Laminar pipe flow- 3D post processing

May 31, 2011, 11:05 am
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I'm new to COMSOL Multyphisics. I succesfully built a 3D model of Laminar pipe flow. These are the conditions and geometery paprameters I used.

Length of the pipe= 0.05m
Radius of the pipe= 0.001m
Density of the fluid= 1000kg/m^3
Viscosity of the fluid= 0.05 Pa*s
Inlet pressure= 400Pa
Outlet Pressure= 0Pa

Reynolds number is 40

Boundary conditions :
No slip walls
Inlet= Pressure, no viscous stress P0=400Pa
Outlet=Pressure P0=0Pa

Stationary

I got my Vmax = 0.0412 m^2/s with a Extra coarse mesh.

Problems:

When ever I tried to use a finer mesh than this it gives me an error saying " "Failed to find a solution. Out of memory during LU factorization. Returned solution has not converged." or " Out of memory in stationary solver" .

For post processing, I want to plot Volumetric flow rate (Q m^3/s) vs Viscosity (mu) and Q vs Radius (m).

Can somebody let me know why i'm getting error messages when I tried to use a finer mesh and please give me some information that will help me and get me started on post processing.



Thank you
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Electromagnet

July 26, 2011, 2:15 am
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Hello,

I would like some advice on the best way to approach this problem. I have tried and tried with various different physics types and boundary conditions:

I am modeling an electromagnet, with the end goal of solving for the electric and magnetic field due to the electromagnet. I have created a geometry with a helix (the current carrying coil) and an iron core. What I would like to do is specify a current flowing through the wire coil and vary that parametrically to see the variation in B and E field strength.

I will eventually place this model in an air-filled box to see how the field propagates in air.

The model I have attached is just the geometry with no physics attached to it, because I'm not sure which the most appropriate. I presume that 'magnetic and electric fields' is the way to go because those are the two quantities I would like to measure but I could be wrong.

Help is greatly appreciated.
Kind Regards,

Dominic.
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Design optimization for iron loss minimization in induction machine (IM)

October 27, 2011, 12:49 am
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Hi all,
I have a model of an induction machine, which is attached in the file. In this model, besides stator and rotor laminations there are still holes located in the stator lamination that I try to make to change the rotational iron loss in the machine. These holes may be for ventilation system. Assuming that, across area of holes is kept constant. But the shape and position of these holes will influence the magnetic flux density as well as magnetic field strenght, then resulting changes on iron losses of the stator core. Therefore, to find an optimal position, we need an optimization method in the comsol model.

Based on this, I have some questions that I need your help.
1- How to build up a iron loss model (or hysteresis loss model) in the induction motor model? So far I do not know how to obtain iron loss distribution in the model. I want to compare iron loss distribution with and without holes.
2- Is it possible to adopt an optimization method to obtain optimal location of holes, which offers a minimum iron loss. Genetic algorithm can be used or developed in Comsol? Is there any references about this?

I believe that there are some guys interested in this problem and having a lots experiences on it with Comsol. I appreciate your help or useful comments that we can learn together.
Thank you so much.

Best,
TUNG
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Single-turn coil gap feed problem

January 26, 2015, 12:35 pm
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Hello,

I am trying to model gradient coils for use in MRI. I created a saddle coil geometry and I tried to run a study with the current direction specified by gap feed, but it fails to find a solution. I've attached my model to the thread, I would appreciate any insight into this.

Thanks in advance!
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Create time-averaged 2d surface plot

February 18, 2015, 12:03 am
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Hello everyone,
I’m trying to model a DBD plasma actuator using the DC discharge module. A sinusoidal signal of 5kV and 1kHz is applied to the electrode and a time dependent study is performed for 10 periods, from 0 to 10 ms. I’m able to create a 2D surface plot of the body force at different times, but I’m also interested to build a 2D surface plot of time-averaged body force (on a period). How can I do this?

Thanks

Chiara
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Modeling of fluid flow caused by deformable objects.

March 13, 2015, 1:45 pm
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I have a stationary object in a stationary fluid at t=0s. At that time, the object (a fixed rectangle) starts moving in a sine wave (eg how flagella or cilia move). Due to this the fluid around it gets moved. I cannot model it, I dont know which model to use and which physics to use to model such a flow.
I have already looked at the example for modelling in fluid structure interaction system. I do not know how to modify the boundary condition do that the rectangle will start moving.
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Recovery files not found

March 13, 2015, 7:24 pm
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I recently had a model crash. I went to open the recovery file, and the Open Recovery File "directory" is showing no files. I verified that there are folders with models in the directory I save my recovery files to, and I have opened recovery files in the past. I am using a -tmpdir command to redirect the recovery files. I also tried changing the comsol.ini file to redirect the path, but that did not seem to help. I am using an Linux OS.

Does anyone know why COMSOL can no longer see my recovery files and if there is some way to redirect the Open Recover File "directory" to the right location?

Thank you
Ian
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mems micropump simulation

March 13, 2015, 8:55 pm
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can any one help me simulate the micropump...........i am not able to simulate the 2d geometry of micropump.i have attach my paper .please some one help me.......................
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About Computing Capacitance in Model Gallery Model ID: 12689

March 13, 2015, 11:42 pm
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Hi everyone,

Recently I learned the "Computing Capacitance" in Model Gallery, the link is

www.comsol.com/model/computing-capacitance-12689

But there is one thing that I did not catch. Why they use glass as the insulating part, but other parts are set as air? Are they supposed to have metal plates as conductor? If i change the material of the plates to be copper, the results seem to be wired. Can anyone help me? Thanks so much!

Best,
Shan
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Problem with skin effect

March 14, 2015, 3:47 am
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Hi,
I am novice in COMSOL.
I would like to obtain temperature distribution during current flow along aluminium plate. The current value is 100A.
I used Magnetic Fields and Heat Transfer in Solids physics. I obtained current density distribution.
I have problem with temperature distribution. In Heat Transfer in Solids I used heat flux, but I didn't obtain result.
Could someone help me?

Thanks,
Michael
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Consumption of species

March 14, 2015, 4:47 am
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Hello everyone,

I have a question because I'm not quite sure how to model it. I have a reactor (square) which contains a chemical component A. A can react to B with the help of a catalyst. I want to simulate the consumption on the right side of the reactor (lets say A can diffuse in the whole reactor) with respect to the generation of B.

I'm not quite sure which modules to use. I tried with the diluted species (and maybe surface reaction modul?); But I don't know how I can set this up with the diluted species module.

Thanks for you help. I appreciate it.

regards Mika
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Snow medium/material

March 14, 2015, 7:13 am
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Is snow material available in COMSOL library? If not, how can I generate the same.
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Fail to create boundary layer mesh for domains

March 14, 2015, 1:01 pm
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Hi there,

I encountered an issue when I was trying to mesh my quite simple geometry. I wanted to use Boundary layers to get the model finer at the boundaries. But I got the error message which said : Could not shift boundary node at all.

Does anybody have ideas how to solve this problem?
many thanks
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